Research Contribution 9f May 1995 THE REPRODUCTIVE ECOLOGY OF BROADLEAVED TREES AND SHRUBS: GLOSSARY by Edward C. Jensen and Debra J. Anderson College of Forest Research Laboratory Forestry Oregon State University The Forest Research Laboratory of Oregon State University was established by the Oregon Legislature to conduct research leading to expanded forest yields, increased use of forest products, and accelerated economic development of the State. Its scientists conduct this research in laboratories and forests administered by the University and cooperating agencies and industries throughout Oregon. Research results are made available to potential users through the University’s educational programs and through Laboratory pub- lications such as this, which are directed as appropriate to forest landowners and managers, manufacturers and users of forest products, leaders of govern- ment and industry, the scientific community, and the general public. The Authors Edward C. Jensen is assistant professor in the Department of Forest Resources, College of Forestry, Oregon State University, Corvallis, Oregon. Debra J. Anderson is a forester and natural resource educator for the USDA Forest Service, Umpqua National Forest, Roseburg, Oregon. To Order Copies Copies of this and other Forest Research Laboratory publications are available from: Forestry Publications Office Oregon State University Forest Research Laboratory Corvallis, Oregon 97331-7401 Please indicate author(s), title, and publication number if known. Recycled Paper THE REPRODUCTIVE ECOLOGY OF BROADLEAVED TREES AND SHRUBS: GLOSSARY Glossary of Terms for Reproductive Ecology This glossary was designed to support an educational program on the reproductive ecology of broadleaved trees and shrubs. Although it includes many terms commonly used in forest ecology and silvicul- ture, it is not a comprehensive list of important terms in those fields. Achene Achene: A small, dry indehiscent fruit formed from a single-carpel ovary; achenes typically contain a single seed and are often dispersed by means of a plumed or feathery tail. The fruits of bitterbrush, sage- brushes, and mountain-mahoganies are achenes. Acorn: A nut topped with a scaly or bristly cap (called an involucre). The fruits of oaks and tanoaks are acorns. Adventitious: Plant organs are said to be adventitious when they arise Acorn in unexpected places—for example, roots that develop from the stem, or buds that develop from the cambium rather than from the apical meristem. Aggregate: Multiple-seeded fruits in which each seed is borne inside its own fleshy covering. The fruits of raspberries and blackberries are aggregates of drupelets; the fruit of yellow-poplar (Liriodendron) is Aggregate an aggregate of samaras. Ament (catkin): A long, narrow inflorescence composed of numerous flowers; typically unisexual (all male or all female). May be erect or pendulous. Wind pollinated. Angiosperm: A class of vascular seed plants characterized by flowers with male and female organs and ovules that are enclosed within ovaries; following fertilization, the ovary develops into a fruit. Asexual reproduction: The formation of new individuals without the production of gametes or special reproductive structures. Because the exchange of genetic material between individuals is not involved, “parents” and “offspring” are genetically identical to one another. Berry: A fleshy, multiple-seeded fruit that does not burst open (de- hisce) at maturity; seeds are typically arranged loosely within the fruit. The fruits of salal, huckleberries, currants, and tomatoes are berries. Broadleaf: Plants with wide-bladed leaves, such as Oregon white oak Berry or bigleaf maple. Always refers to flowering trees and shrubs (an- giosperms), in contrast to conifers or cone-bearing trees (gymno- sperms); may be deciduous or evergreen, depending on how long 1 their leaves live. Broadleaved trees are often called hardwoods, al- though not all of them have hard wood. Browse: As a verb, browse means to eat the twigs and leaves of plants. As a noun, it refers to the twigs and leaves eaten by browsing ani- mals. Deer and moose are browsers. Bud: An undeveloped shoot consisting of a shortened stem and embry- onic leaves or flowers. Most buds are enclosed in modified leaves called scales, although some are naked. Buds borne at the ends of branches are called terminal; buds borne in the axils of leaves are called lateral; buds that arise in unpredictable locations are called adventitious. Canopy: The layer formed by leaves and branches of the forest’s tallest plants. A canopy in which the branches of neighboring plants touch Capsules is called a closed canopy; if branches do not touch, the canopy is called open. Capsule: A dry, multiple-seeded fruit formed from several fused car- pels; the carpels split open (dehisce) at maturity to release their seeds. The fruits of rhododendrons, cottonwoods, willows, and mockorange are capsules. Carpel: The female reproductive organ of a flowering plant, including the ovary, stigma, and style. A simple pistil or a single member of a compound pistil. Catkin (ament): A long, narrow inflorescence composed of numerous flowers; typically unisexual (all male or all female). May be erect or pendulous. Wind pollinated. Clearcut (clearcutting): The removal of all trees in a stand in a single cutting. A method of regenerating an even-aged stand in which the new age class develops in a fully exposed microclimate. Clone: An individual or group of individuals that are genetically identi- Catkin cal to a single parent plant. Clones result from asexual (vegetative) (ament) propagation. May be used as a noun or a verb. Community: Used in several ways with small, but significant, differ- ences. Sometimes refers to groups of similar life forms within a given area (e.g., the plant community or the animal community of a site); sometimes refers to all living organisms within a particular habitat or site. Conifers: Plants that bear their seeds inside woody or semi-woody stro- biles commonly called cones; all conifers are gymnosperms, but not all gymnosperms are conifers. Similarly, most conifers are needle- leaved trees, but not all needle-leaved trees are conifers (yews, for example, do not bear cones). Most conifers are evergreen, but some, such as the larches, are deciduous. Examples of conifers include the pines, spruces, larches, true firs, hemlocks, and Douglas-fir. Deciduous: Falling off at the end of a growing season or following a particular stage of development. Most North American broadleaved Dehiscent trees have deciduous leaves; Pacific Northwest examples include Or- egon white oak, vine maple, red alder, and the willows. Only a few conifers have deciduous leaves; larches and baldcypresses are ex- amples. The opposite of deciduous is persistent. Dehiscent: Splitting along one or more pre-determined sutures at ma- turity. Many dry fruits are dehiscent; they split open, sometimes 2 violently, to expel their seeds. Legumes, capsules, and follicles are all dehiscent; nuts, samaras, and achenes are not. Disturbance: Any relatively discrete event that disrupts the organisms or the physical environment of a site. Common examples are fire, wind, flood, and landslides. Drupe: A fleshy fruit usually containing a single, hard seed. The fruits Drupe of cherries, plums, cascara buckthorn, and poisonoak are drupes. Drupelet: A small drupe. The fruits of raspberries and blackberries are aggregates of drupelets. Ecology: The science that deals with the relation of plants and animals to their environment and to the factors that control their reproduc- tion, distribution, and growth. Ecosystem: A term meaning ecological system. An ecosystem is made up of all the organisms living in an area, the physical environment that surrounds them, and the processes by which they interact. The term ecosystem represents a concept rather than a discrete, physical entity. Any boundaries drawn around an ecosystem are arbitrary. Environment: The complete range of external conditions in which an organism lives. Includes physical, biological, and chemical factors. Evergreen: Always green; a plant that adds new leaves before losing its older leaves is called an evergreen. Among trees, most conifers are evergreens; in temperate regions of the world most broadleaved trees are deciduous, but in tropical regions most are evergreen. Follicle Follicle: A dry, multiple-seeded fruit formed from a single carpel that splits open along one side at maturity. The fruits of ocean spray, ninebark, and spirea are follicles. Forage: As a verb, forage means to graze or eat. As a noun, it refers to leaves and other plant parts eaten by herbivorous animals. Forest: A complex assemblage of plants, animals, and environment domin- ated by trees. Fruit: The ripened ovary of a flower that develops following fertiliza- tion; seeds are contained within fruits. Fruits vary considerably in form, size, shape, and texture, depending on how they are to be dispersed. Apples and cherries are common fruits. Fruit Germination: The initial emergence of roots, shoots, and leaves from a seed. Germination usually follows a period of dormancy and gener- ally occurs in response to favorable external conditions, including warmth, moisture, and oxygen. Gymnosperm: A class of vascular plants (mostly trees) that bear naked seeds—that is, seeds not enclosed inside ovaries. Some gymnosperms bear their seeds inside female strobiles commonly called cones; members of this group are called conifers. Habitat: The physical environment